Photoshop CC 2015: Swatches window - color mismatch

ISSUE: The color of the fill is not the same as the color I picked from the "Swatches" window

How to reproduce:
1. File > New (RGB Color, 8 bit, Don't Color Manage this Document)
2. Turn on the "Info" window
3. In the "Swatches" palette locate the 50% Gray and move the mouse cursor over the color. In the "Info" window you will see the following RGB values: (R=128,G=128,B=128). Now, click on the color to make it active.
4. Fill in the image with the "Paint Bucket Tool" (No Anti-alias)
5. Pick the "Eyedropper Tool" and move the cursor over the image. In the "Info" window you will see these RGB values: (R=127,G=127,B=127)

So the color of the image (R=127,G=127,B=127) is different than the color you have choose (R=128,G=128,B=128) in the "Swatches" window and used for the fill.

I am in hurry so I have to be brief. The problem will be somewhere in the Paint Bucket Tool because when I switch to Pencil Tool the color is always (128,128,128). When I am using Paint Bucket Tool on the same image the color is (127,127,127).